According to the PROYECTO DE REAL DECRETO POR EL QUE SE APRUEBA EL PROCEDIMIENTO BÁSICO PARA LA CERTIFICACIÓN DE LA EFICIENCIA ENERGÉTICA DE LOS EDIFICIOS following aspects will be measured when evaluating the energy category of a building or house: a) Design, location and orientation of the building. b) Environmental conditions indoor and outdoor climate. c) Thermal characteristics closures. d) Passive solar systems and solar protection. e) Thermal installations of individual and collective buildings (heating, cooling and hot water production) and systems heating and cooling, including the characteristics of Insulation of pipes and ducts. f) Natural and mechanical ventilation. g) Installation of artificial indoor lighting. h) Natural lighting. i) Active solar systems and other heating systems or production electricity based on renewable energy sources. j) Electricity from cogeneration. For more information visit the Ministerio de Industria, Energía y Turismo website.